A widely used instrument used by ophthalmologists for eye examinations is called a "slit lamp" biomicroscope (slit lamp diagnostic microscope). The instrument consists, generally, of fixed-frame posts supporting a headrest to receive the chin and forehead of a patient, and a movable base. A stereomicroscope is mounted on the base and the base is moved, in the X-Y-Z directions, by the user. A lamp is mounted to shine on the eye being examined and a control device, in front of the lamp, produces a slit of light, e.g., an elongated line of light of about 100,000 to 600,000 Lux.
That slit of light is focused on the patient's eye. Some slit lamps permit the length of the beam to be changed, i.e., 0.2 to 8 mm or more, and to be rotated about the patient's head and to be angled, i.e., rotated 20 degrees from vertical. The ophthalmologist looks at the eye being examined, generally through a stereo microscope mounted on the stand and also through a lens which is generally held by hand.
This type of slit lamp is available from Haag-Streit AG, i.e., Model 900 BQ; Rodenstock, i.e., Model RO 5000; Reichert, i.e., Model Xcel; D. F. Vasconcellos; Nikon; and others.
Although this type of slit lamp has proven satisfactory for eye examinations, it is not adapted for precision electronic/digital photography of the eye. For example, in "telemedicine" a patient at a local facility (for example, a small-town ophthalmologist office) is being examined. A photograph (video or still picture) of his eye is transmitted, in real time, to a center (for example, a university hospital) to obtain a consultation by a cornea specialist. A picture of the eye is taken using a high-resolution color digital camera, transmitted over a broadband telecommunication channel and displayed on a high-resolution monitor. However, the picture may not be satisfactory to provide an accurate remote diagnosis because the slit lamp's illumination of the patient's eye is not illuminated satisfactorily for accurate photography. The ophthalmologist, using his eyes and skill, can see more than shows in a high resolution digital photograph.
U.S. Pat. No. 5,196,874 is entitled "Slit Lamp Apparatus With Peripheral Illumination." It, and the present invention, provide an auxiliary lamp (additional illuminating device) to shine on the eye undergoing examination in addition to the slit illuminating device. The '874 patent's auxiliary lamp is a tube which is rotatably mounted on the slit lamp frame.
Other patents that relate to slit lamps include U.S. Pat. Nos. 4,868;383; 3,403,957; 5,099,354; 3,652,153; and 5,018,851; the above-listed patents being incorporated by reference.